1. Field of the Invention
The present invention relates generally to electrical toggle switches of a type normally used to control AC power to resistive and inductive loads, motor loads and lighting, or the like, and more particularly to a toggle switch which is specifically designed to be used in potentially explosive environments.
2. Description of the Related Art
Toggle switches of various types have long been used to control AC power in domestic, commercial and industrial applications for operating various electrical devices and equipment. Known toggle switches typically are manufactured with a dielectric housing that contains electrical contacts and is fitted with a manually operable handle to switch power to externally mounted terminals. In one common form of toggle switch the handle has a cam surface internal to the housing that actuates a metallic leaf spring which in turn makes or breaks electrical conductivity with the contacts. Common toggle switches are standardized in terms of their mounting configurations such that they can readily be installed in wall-mounted electrical boxes, for example, with only the use of two screws. Typically, screw terminals are positioned on the sides of the switch housing such that connection can be easily made to electrical wires of suitable size to deliver AC power to electrical devices or equipment.
The common toggle switch is generally unacceptable for use by itself in an environment that can contain potentially explosive gases. This is so because the housing is generally not designed to allow gases that result from contact arcing to circulate within the housing and exit at a temperature that is below the ignition temperature of the surrounding gases. Accordingly, where conventional toggle switches are used in potentially explosive environments they generally must be housed in a specially designed enclosure. Not only can such enclosures be expensive to manufacture, they are not capable of being fitted into a standard electrical box, and therefore, they must be specially installed at additional cost to the user. In addition, common forms of toggle switches have side mounted electrical terminals for connection to electrical wiring. These terminals can short circuit to metal boxes in which the toggle switches are installed unless extra steps are taken to protect them using electrical tape or the like. Accordingly, it is desirable to provide a toggle switch of a unique construction which is not only explosion proof when used in an explosive environment but which is also of a size capable of permitting the switch to be installed conveniently in a standard, ordinary electrical box. It is also desirable to provide such a switch having a unique arrangement of terminals such that the terminals are preprotected from shorting to a metal electrical box in which the switch is installed. Still further, it is desirable to provide such a switch which is cost effective to manufacture by conventional methods.